Calculation of Leakage Reactance in Transformers with Constructive Deformations in Low Voltage Foil-Windings

MOMBELLO, ENRIQUE ESTEBAN; GUIDI, GUILLERMO; DIAZ, GUILLERMO ANDRES

IEEE TRANSACTIONS ON POWER DELIVERY

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Año: 2018 p. 1 - 6

0885-8977

Foil-winding transformers with high currents in low voltage winding normally have copper/aluminum bars as leads of the coils. A practical solution for locating bar leads without increasing the size of the active part is to flatten the coil in the leads zone causing a deformation. Abnormalities in the leakage reactance have been identified in this type of transformers. In order to take this effect into account, this work proposes a correction to the mathematical formulation for calculating the leakage reactance in transformers with  deformations in the low voltage winding. Three methods for calculating the leakage reactance have been compared for four real case studies: the proposed formulation, the commonly used formulation and detailed simulations with the finite element method in 3D (FEM3D). The leakage reactance calculated with the proposed method has been found to have an improved accuracy compared with the one calculated using the formulation without correction in all case studies. The main contribution of this work is that the proposedcorrection in the formulation makes it possible to increase the accuracy in the calculation of leakage reactance, avoiding the need to resort to detailed simulations with FEM3D.